COMPOSITION AND METHOD FOR POLISHING MOLYBDENUM
The present invention provides compositions and methods for polishing a molybdenum metal-containing surface. A polishing composition (slurry) described herein comprises an abrasive concentration of an inorganic particulate abrasive material (e.g., alumina or silica) suspended in an acidic aqueous medium containing a water soluble surface active material and an oxidizing agent. The surface active material is selected based on the zeta potential of the particulate abrasive, such that when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative zeta potential, the surface active material comprises an anionic material, a non-ionic material, or a combination thereof.
1 . A chemical-mechanical polishing (CMP) method for polishing a molybdenum-containing substrate comprising the steps of:
(a) contacting a surface of the substrate with a polishing pad and an aqueous CMP composition comprising an aqueous carrier having a pH in the range of about 3 to about 6 and containing, at point of use:
(a) a particulate abrasive selected from the group consisting of a silica abrasive and an alumina abrasive;
(b) a water soluble surface active material; and
(c) an oxidizing agent;
wherein the surface active material is selected based on the zeta potential of the particulate abrasive, such that when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative zeta potential, the surface active material comprises an anionic material, a non-ionic material, or a combination thereof; and
(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the molybdenum from the substrate.
2 . The CMP method of claim 1 wherein the particulate abrasive comprises alpha-alumina and the surface active agent is a cationic material.
3 . The CMP method of claim 2 wherein the cationic material is a cationic polymer.
4 . The CMP method of claim 3 wherein the cationic polymer comprises a poly(methacryloxyethyltrimethylammonium)halide.
5 . The CMP method of claim 3 wherein oxidizing agent comprises hydrogen peroxide.
6 . The CMP method of claim 1 wherein the particulate abrasive comprises silica and the surface active material is an anionic material, a non-ionic material or a combination thereof.
7 . The CMP method of claim 6 wherein the surface active material comprises a poly(acrylic acid), a polyacrylamide, or a combination thereof.
8 . The CMP method of claim 6 wherein oxidizing agent comprises hydrogen peroxide.
9 . The CMP method of claim 1 wherein the particulate abrasive comprises an aminosilane surface-treated silica having a positive zeta potential, and the surface active material comprises cationic material.
10 . The CMP method of claim 9 wherein the cationic material is a cationic polymer.
11 . The CMP method of claim 10 wherein the cationic polymer comprises a poly(methacryloxyethyl trimethylammonium)halide.
12 . The CMP method of claim 9 wherein the oxidizing agent comprises hydrogen peroxide.
13 . The CMP method of claim 1 wherein the oxidizing agent comprises hydrogen peroxide.
14 . A chemical-mechanical polishing (CMP) method for polishing a molybdenum-containing substrate comprising the steps of:
(a) contacting a surface of the substrate with a polishing pad and an aqueous CMP composition comprising an aqueous carrier having a pH in the range of about 3 to about 6 and containing, at point of use:
(i) about 0.5 to about 6 wt % of a particulate abrasive selected from the group consisting of a silica abrasive and an alumina abrasive;
(ii) about 25 to about 5,000 ppm of a water soluble surface active material; and
(iii) about 0.1 to about 1.5 wt % of an oxidizing agent.
wherein the surface active material is selected based on the zeta potential of the particulate abrasive, such that when the abrasive has a positive zeta potential, the surface active material comprises a cationic material, and when the particulate abrasive has a negative zeta potential, the surface active material comprises an anionic material, a non-ionic material, or a combination thereof; and
(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the molybdenum from the substrate.
15 . The CMP method of claim 14 wherein the particulate abrasive comprises alpha-alumina or an aminosilane surface-treated silica, and has a positive zeta potential, and the water soluble surface active material comprises a poly(methacryloyloxyethyl trimethylammonium)halide.
16 . The CMP method of claim 15 wherein the oxidizing agent comprises hydrogen peroxide.
17 . The CMP method of claim 14 wherein the particulate abrasive comprises a silica having a negative zeta potential, and the water soluble surface active material comprises a poly(acrylic acid), a polyacrylamide, or a combination thereof.
18 . The CMP method of claim 17 wherein the oxidizing agent comprises hydrogen peroxide.